Transcript chapter39_Animal Behavior(5

Cecie Starr
Christine Evers
Lisa Starr
www.cengage.com/biology/starr
Chapter 39
Animal Behavior
(Sections 39.5 - 39.9)
Albia Dugger • Miami Dade College
39.5 Communication Signals
• Communication signals play a role in both cooperative and
competitive behavior
• communication signal
• Chemical, acoustical, visual, or tactile cue that is produced
by one member of a species and detected and responded
to by other members of the same species
Communication Signals (cont.)
• Pheromones are chemical signals
• Examples: honeybee alarm pheromone, sex attractants,
priming pheromones
• Bird song and other animal calls are acoustical signals
• Attracts mates, defines territories, conveys alarms
Communication Signals (cont.)
• A male baboon’s threat
display is a visual signal
that communicates
readiness to fight a rival
Communication Signals (cont.)
• Most bird courtship
involves coordinated
visual signaling
Communication Signals (cont.)
• Dogs and wolves signal play behavior with a play bow
Communication Signals (cont.)
• Honeybees use tactile signals to communicate the distance to
a food source, and its direction relative to the sun
Communication Signals (cont.)
When bee moves straight
up comb, recruits fly
straight toward the sun.
Fig. 39.11c, p. 663
Communication Signals (cont.)
When bee moves straight down
comb, recruits fly to source
directly away from the sun.
Fig. 39.11d, p. 663
Communication Signals (cont.)
When bee moves to right
of vertical, recruits fly at
90° angle to right of the sun.
Fig. 39.11e, p. 663
Honeybee Dances
Honeybee Dances
Fig. 39.11a, p. 663
Honeybee Dances
Fig. 39.11b, p. 663
Honeybee Dances
When bee moves
straight up comb,
recruits fly straight
toward the sun.
C
When bee moves
straight down
comb, recruits fly
to source directly
away from the sun.
D
When bee moves
to right of
vertical, recruits
fly at 90° angle
to right of the
sun.
E
Stepped Art
Fig. 39.11, p. 663
ANIMATION: Honeybee dances
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Adaptations by Predators
• Predators sometimes use the signaling systems of their prey
against them
• Frog-eating bats follow the frogs’ mating calls to find food
• Predatory female fireflies imitate flashing of prey species to
attract food
Key Concepts
• Animal Communication
• Animal communication behavior can only evolve if
communication benefits both signal senders and signal
receivers
• Animals communicate by a variety of mechanisms
• Predators sometimes take advantage of the
communication behavior of their prey
39.6 Mates, Offspring, and Reproductive
Success
• Sexual selection occurs when males or females of a species
compete for access to mates, or when they are choosy about
their mates
• Parenting behaviors can also reflect different selective
pressures operating on males and females
Mating Behavior
• Sexual selection favors characteristics that provide a
competitive advantage in attracting and retaining mates
• Males usually maximize their reproductive success by mating
as many times as possible
• Females are more likely than males to turn down
opportunities to breed with a low-quality individual
Sexual Selection
• Male hangingfly offers a
moth to a potential mate
• Female hangingflies
only breed with males
who provide an energyladen meal
Sexual Selection
• Female fiddler crabs
choose mates with large
claws who have built a
burrow with the right
location and size
Sexual Selection
• Male grouse converge
at a lek to attract a
mate by displaying,
dancing and calling
• lek
• Of some birds, a
communal mating
display area for males
Mating Behavior (cont.)
• In species such as lions, elk, elephant seals, and bison;
females cluster around a necessary resource, and males may
hold a territory that they defend from others
• The territory holder mates with all females in his territory
• territory
• Region that an animal or animals occupy and defend
against competitors
Male Bison Defending his Territory
Mating Behavior (cont.)
• When females choose among a group of displaying males or
males defend a mating territory, nearly all females mate but
many males do not
• These systems impose strong selective pressure for matingrelated traits on males (sexual dimorphism)
• sexual dimorphism
• Distinct male and female phenotypes
• Example: Large claws in male fiddler crabs
Parental Care
• Evolution of parental care requires that benefits to a parent
(increased offspring survival) be greater than the cost (lost
reproductive opportunity)
• Mammals are usually born in a helpless state, so parental
care is essential – typically, the female is the sole caregiver
• Example: A female grizzly bear cares for her cub for as long
as two years; the male takes no part in its upbringing
Female Grizzly and Cub
Parental Care (cont.)
• Males seldom serve as
sole caregivers
• The midwife toad is an
exception: a male holds
fertilized eggs around
his legs until the eggs
hatch
Parental Care (cont.)
• Most birds are
monogamous, and
parents cooperate in
caring for young
• Example: Caspian terns
Key Concepts
• Mating and Parenting
• Males and females maximize their reproductive success in
different ways
• Females tend to be choosier about mates than males
• Monogamy is rare among animals, but it tends to correlate
with parental care by both parents
• More often, the female provides parental care
39.7 Living in Groups
• Many animals benefit by
clustering in groups
• Birds, monkeys,
meerkats, and other
animals in social groups
make alarm calls in
response to a predator
• Example: Prairie dog
Defense Against Predators
• Sawfly caterpillars
benefit by the group’s
coordinated response to
predators
• Predatory birds to avoid
the mass of fluidexuding caterpillars,
preferring to attack
individuals
Defense Against Predators
• When animals cluster, some individuals shield others from
predators – preference for the center of a group can create a
selfish herd, in which individuals hide behind one another
• selfish herd
• Temporary group that forms when individuals cluster to
minimize their individual risk of predation
Defense Against Predators:
Musk Oxen Protecting Young
Improved Feeding Opportunities
• Many mammals (such as wolves, lions, wild dogs, and
chimpanzees) live in social groups and cooperate in hunts
• Cooperative hunters are not more efficient than solitary ones;
the major advantage of group living lies in help fending off
scavengers, caring for one another’s young, and protecting
territory together
Wolf Pack Hunting
Feeding Opportunities (cont.)
• Group living also allows transmission of cultural traits, or
behaviors learned by imitation
• Example: Chimpanzees make and use simple tools
• They use thick sticks to make holes in a termite mound,
then insert long, flexible “fishing sticks” into the holes
• Different groups of chimpanzees use slightly different toolshaping and termite-fishing methods
• Youngsters learn by imitating adults
Behavior Learned by Imitation
Dominance Hierarchies
• Many animals in permanent groups form a dominance
hierarchy in which dominant animals get a greater share of
resources and breeding opportunities than subordinate ones
• Example: In wolf packs, usually only the alpha male and
alpha female breed; subordinates get their chance to
reproduce by outliving a dominant peer
• dominance hierarchy
• Social system in which resources and mating opportunities
are unequally distributed within a group
Regarding the Costs
• In most habitats, costs of social living outweigh the benefits
• Large social groups attract more predators
• Individuals that live in dense groups have higher risks of
parasites and contagious diseases, and compete more for
resources
• Example: Seabirds in dense breeding colonies
Crowded Penguin Breeding Colony
Video: Wolf Pack
39.8 Why Sacrifice Yourself?
• Extreme cases of sterility and self-sacrifice have evolved in a
few insects and one group of mammals
• Ants, termites, honeybees, and mole-rats are eusocial – they
live in colonies with overlapping generations and have a
reproductive division of labor
• Most colony members do not reproduce; they assist their
relatives instead
Sterile Workers
• Workers often are highly specialized in form and function
• Example: Australian honeypot ant worker
Sterile Workers
Honeybees
• A queen honeybee is the only fertile female in her hive
• Sterile female workers feed larvae, clean and maintain the
hive, construct honeycomb, gather nectar and pollen, and will
sacrifice themselves to guard the hive
• Male stingless drones (produced seasonally) subsist on food
gathered by their worker sisters; and fly each day in search of
a mate
Termites
• A termite queen specializes in egg production
• A king supplies the female with sperm
• A termite mound holds both sterile males and females
• Winged reproductive termites of both sexes develop
seasonally
Social Mole-Rats
• Sterility and extreme self-sacrifice are uncommon in
vertebrates – mole rats are the only example
• A reproducing female (“queen”) dominates the clan and
mates with one to three males (“kings”)
• Sterile clan-members guard the colony; or excavate tunnels
and chambers, find food, and carry it back to the queen, her
mates, and her young
Three Queens
Evolution of Altruism
• A sterile worker in a social insect colony or a naked molerat
clan shows altruistic behavior
• Inbreeding increases the genetic similarity among relatives
and may play a role in mole-rat sociality
• According to the theory of inclusive fitness, genes
associated with altruism are selected if they lead to behavior
that promotes reproductive success of close relatives
Key Terms
• altruistic behavior
• Behavior that benefits others at the expense of the
individual
• theory of inclusive fitness
• Genes associated with altruism can be advantageous if
the expense of this behavior to the altruist is outweighed
by the reproductive success of relatives
Key Concepts
• Costs and Benefits of Social Living
• Life in social groups has reproductive benefits and costs
• Not all environments favor the evolution of such groups
• Self-sacrificing behavior has evolved among a few kinds of
animals that live in large family groups
39.9 Evolution and Human Behavior
• Calling a behavior “adaptive” does not mean “morally right,” it
means a behavior increases reproductive success
• Example: Infanticide is morally repugnant, but it happens in
all human cultures – when mothers lack resources to care for
their children, they are more likely to harm them
• Evolutionary forces shape and influence human behavior –
but humans can make moral choices about their actions
An Aggressive Defense (revisited)
• When a European queen bee mates with an Africanized
drone, her offspring are just as aggressive as workers in a
pure Africanized colony
• A cross between an Africanized queen and a European drone
yields workers with an intermediate level of aggression
• Unfortunately, Africanized males outcompete European males
for matings